i have noticed recently, my bike has a slightly noticeable splutter at around 6k'rpm when WoT thru the gears, just before the ole poweband kiks in, she just sorta , clears her throat' for lack of better explanation..

no flat spot, there doesnt seem to be a problem with power delivery,, but im worried this is what its eluding too.

Im thinking a replacement of spark plugs and a carby tune may alleviate my issue. Any ideas appreciated cheers
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Last edited by Kubira on Tue Jul 07, 2009 12:59 pm; edited 1 time in total

Kubira wrote:
Im thinking a replacement of spark plugs and a carby tune may alleviate my issue, but as im workin a lot now , i havent the time... ... Any ideas appreciated cheers

Be prepared for it to become extremely expensive very quickly then, if you "don't have the time" to maintain any 2-stroke.

Time is one thing all 2-strokes require.
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Andy.
NSR-WORLD.COM

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I can vouch for that! 2 NSRs, both needed full engine rebuilds to get them right, and countless hours in the workshop.
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Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30

I agree with your point chaps a two stroke will require time and a bit of spanner work.

Whats with the negativity though? I think a well maintained used NSR given a once over after purchase should be one of the most reliable 250 2T's money can by.

My old MC16 was used regularly for 2 years never ever let me down.

Some 2 strokes require more maintenance then others. My NSR's have required the most of any Stroker that I've ever owned for some reason.

It's also the oldest 2 stroke I've ever owned which does explain some of the issues.


Last edited by apexxn on Wed Jul 08, 2009 12:38 am; edited 1 time in total

jimmy13 wrote:I agree with your point chaps a two stroke will require time and a bit of spanner work.

Whats with the negativity though? I think a well maintained used NSR given a once over after purchase should be one of the most reliable 250 2T's money can by.

My old MC16 was used regularly for 2 years never ever let me down.

Its not negative, I actually enjoy the engine rebuilds, just don't enjoy the costs But a good point, once you have rebuilt the engine you have a datum point. Then as long as its set-up right, the engine should run reliably (relative to 2 strokes in general - its never going to be a 50,000 mile - no work scenario). The main issue is buying a 2 stroke of unknown engine condition and thinking it will run great for ever more. Also with the age of NSRs, dead crank seals are a perenial issue, even if the crank / pistons / barrels etc are OK.
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Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30

Kubira wrote:i have noticed recently, my bike has a slightly noticeable splutter at around 6k'rpm when WoT thru the gears, just before the ole poweband kiks in, she just sorta , clears her throat' for lack of better explanation..

no flat spot, there doesnt seem to be a problem with power delivery,, but im worried this is what its eluding too.

Im thinking a replacement of spark plugs and a carby tune may alleviate my issue. Any ideas appreciated cheers

Worth taking the carbs off, cleaning all the jets & bowls & tubes etc and also checking all the jet sizes are standard (providing your bike is standard).
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Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30

RichG wrote:just don't enjoy the costs

To be fair Rich, you can get bikes cheaper and skimp on parts a bit more than you do without too much ill effect
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Please do not PM me technical questions, if you can't find it on the Forum start a thread

Unfortunately John, I think it was skimping on parts (rebuilding a crank and not renewing the big end needle bearings - Parky69) which is probably what ended my track day at Cadwell after just 2 sessions

Personally, If I'm going to all the work of engine out and splitting the cases, I can't see the point in doing half a job and waiting for it to seize again soon after rebuild. Hope my NSRs don't eat more cranks anytime soon

However, I do agree there are much cheaper NSRs out there than the ones I have bought. Purchase price (low or high) is no indicator of mechanical integrity though

But money saved on bike purchase = money available to sort engine.
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Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30

Can we keep vaguely on topic for this guys question, not debate how reliable NSR's are?

How long have you had the bike, and when was it last serviced?

Have you changed anything recently, even something like the type of two stroke oil you're using?
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Sorry Dave!
It would also be useful to know if the bike is standard or has been modified (exhaust / airbox etc).
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Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30

Dave Ett wrote:Can we keep vaguely on topic for this guys question, not debate how reliable NSR's are?

How long have you had the bike, and when was it last serviced?

Have you changed anything recently, even something like the type of two stroke oil you're using?

Cheers Dave

recently, (3 weeks ago), running open carbs after they were cleaned up. One thing i did notice, is after i cleaned out the AS screw hole/screw thread, they tapered in a bit further and now line up when fully in, 1 1/2 turns out etc, whereas they were in different pos. b4. I have 1 3/4 out, sounded smoother when idling there.

150's installed came with the bike, box lid mods, 12 or so 10 ml holes. No pipes to match this mod, but my plugs seem to be ok

prior to above, i had been and still am running premix, castrol tts, always been tts since i bought the bike 3 months ago. bottom thru top rebuild was performed a few track days b4 i buyed it
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how can i make sure theres no dirt in the tiny toob that allows the flow of air, i cleaned the thread part and taper section only. Idk, ill have to check that



i want to blow it out in the direction of the blue arrow, where can i blow??
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Hi Mate
Don`t listen to the negativaty it`s the cold over they nothing likes it .I`ve had no probs in oz with 2 strokes geez i rode my rz250 3hours straight at 9500rpm from tammworth 2 newcastle as did my mate on kr1 .
To the topic i`ve got the same prob with mine at moment bit of a spluter before hitting band .Mine is jetting i`ve put hrc kit in slowly getting it right i`m a bit rich on main still it`s been getting less each jet change .

Do you have access to a dyno? That is the fastest way to get in the right ball park for jetting.

Have you seen the diagram explaining what affects the fuelling at different throttle openings?
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball